Why don't the pirates just destroy the marines?

[Warmmedown]

In real life, the police are stronger than gangs. Except in some places, like Mexico.

In OP, they the Yonkou could flatten tye marines, no?

Kaidou, Big Mom, Shanks, shichibukai and their crews could crush the admirals, Garp, Sengoku, Vice Admirals, SWORD, CP0, CP9.

Then th3 pirates could just fight each other. They don't want a lack of law ajd order?